Fluid pressure trip controlled vacuum breaker



Aug. 17, 1954 L. L. SNYDER 2,536,528

FLUID PRESSURE TRIP CONTROLLED VACUUM BREAKER Filed Feb. 6, 1950 2Sheets-Sheet 1 N I i .49 2|- 24- k &

] 74- w I 80 i k I 1 l2 IO H INVENTOR. 460M980 4. S/VFDEQ Aug. 17, 1954L. L. SNYDER 2,686,528

FLUID PRESSURE TRIP CONTROLLED VACUUM BREAKER Filed Feb. 6, 1950 2Sheets-Sheet 2 85 55 52 55 2| ET 52 22 E NOEMHLVOPEQflIIA G cow/701v q IE604- |5 e 65 ST/ZQIYNG 70 25-857 69 l 54 INVENTOR. 72 450M420 4. saw059 s9 Patented Aug. 17, 1954 UNITED STATES IFLUID PRESSURE TRIP.CONTROLLED VACUUM BREAKER Leonard L. Snyder; Los Angeles,. Calif.,assig'nor t Backfiow Engineering & Equipment Gom- .-pany, Los Angeles,Calif., a corporaticnof California Application February 6, 1950, SerialNo. 142,625

. 17 Claims.

:This .invention relates to backfiow prevention apparatus and. isparticularly directed to. a new and improved type of vacuum breaker.

Vacuum. breakersof the type usedin preventing backfiow from .aconsumers, line to a service :line, for example, commonly utilizesubatmos- .pheric pressure to apply a. force. to open, a valve so thatatmospheric: airm-ay be drawn into the service line and thereby minimizethe possibility of drawing liquid from .a consumers line into a 1service line. It .is important to avoid thelatter possibility becausetheliquid in the consumers .line maybe contaminated, and if such liquid isdrawn. into the. service'line, the contamination may spread throughoutthe system.

It is. important that vacuum breakers'operate instantly .uponsubatmospheric. pressure occurring in theservice-line becauseranyvconsiderable-lag or sluggishne-ss' in operation may allowpolluted liquidto bedrawn into the service line.

.Sinceprivate: and public health'maybe. vitally dependent upon.prevention of iback-siphonage,

itis imperative that the vacuum breaker be reliable in operation. In the.past, "some vacuum breakers haveibeenconstructed having an operationdependent entirely .upon .xsubatmospheric pressure orpartial'vacuumexisting in theservice line. :When the partial vacuum wasvery.slight,

.oftensufficient force was not genera-ted to'open a the breaker, andback-siphonage;occurred.= Other vacuum breakers had been madethat arecontinua'llyiurgedzto an! open: position by a .weight or. spring. .1 Ifthis opening. force were. sufficiently great to insure opening undervacuums :oflow intensity, ,.difi"1culty was experienced. in-LpreVentingexcessive leahageunder low-service line pressures. It is highlydesirableto have'the vacuum breaker open positively upon the slightest vacuumoccurring in.-the service line. .In: fact, inxmany cases itmaybedesirable to have it open slightly before the partial vacuumactually exists and-at the: same time avoid excessive spillage.

Furthermore, this difficulty. is complicated by the fact thatordinarily,vacuum breakervalve assemblies are calledupon tooperateonlyinfrelquently. Long :periods'of time maytpass without any action bythe vacuum breaker, and therefore the moving parts thereof may becomestuck together soathatirictional resistance opposing movement oftheparts is'very'high. fiAccordingIy,

after a long period-Jot inaction'a much greaterpressureudifferentialmaybe required to open the vacuum breaker, andhence gpolluted water :may

- be asucked :zinto tithe. service line. for some time .ebeiorethevacuum breaker. functions.

It isthe principaIQobjec-tof my invention .to

.avoid these: difiiculties'and provide .an-v'acuum :breaker assembly:which .canrbe reliedtuponzto open as soonaas. pressure in the servicelines falls below'appredete-rmined value.

''-Another object of any invention .is to, provide avacuum-breakereinwhich the forces operating to open the: valveparevnotdeveloped bya-reduction in'pressure :iri the service line.

Another .obj ect :is; to, provide a. vacuum breaker assembly havingstored. energy means operable to open the-valve aandxhaving;pressureoperated latch meansi normally maintaining the stored energymeans ineffective.

A more particular object is to provide avacuu-m breaker assembly,havinga spring arranged to -:open a valve and having latch meanseffectiveto hold the springuin-latched position, .thelatch means beingactuatedto. allow thespring to-open the valve whenever the; pressure inthe: service line falls-below apredetermined value.

Other 5 and more detailed objectssandzzadvantages will a-ppearmore fullyhereinafter.

In the'drawings: :Figure ,1 is-ra side-elevation partly in' sectionshowing a preferredrembodimentof my invention. Figure .2 is alongitudinal sectional-elevation showing the partsof the vacuum breakerin nor- Referring to. theidrawings. the: service, line; 1 0

may deliver water under: pressure to the T fitting -H and intothe-consumers line i2. The vacuum breaker assembly; generally.designated 1 3'is also connected to the T:fitting=- I I. .In'general,-,-the function of the vacuum breakerzassembly; I3 is tointroduce: atmospheric air' into .the T fitting ill I and serviceerlineHi. inithezaevent thatsubatmospheric. pressure shoulddevelop :in the.serviceline it. In this way, the possibility of sucking polluted water.from. the ccnsumers :line 12 intotheaservice ...-line it] isminimized.

Referring to Figure l, the vacuum breaker assembly i3 is connected tothe T fitting H by means of a threaded nipple M. The assembly I3includes a central ported body I 5 having an upper flange i6 and a lowerflange ii. A flanged lower end cap 18 is connected to the body flange Hby means of a plurality of bolts i9, and this end cap is threaded at 20to receive the nipple I l. The upper end cap 2| is also flanged, and itis connected to the upper body flange i6 by means of bolts 22. A fixedsleeve 23 is provided with a flange 2 and this flange is also connectedto the body it by means of the bolts 22. The sleeve 23 extends axiallywithin the body 55 and is provided with axially aligned cylindricalbores 25 and 25. The lower end of the sleeve terminates in an annularshoulder 21.

A valve, generally designated 28, includes a stem 29 slidably mountedwithin the bore 26. Formed integrally with the stem is an enlarged head3B which carries a sealing ring 3!. A threaded element 32 cooperateswith a retainer plate 33 for maintaining the sealing ring 3! in positionon the valve head so. A nut 34 threaded on the upper end of the valvestem 29 is adapted to engage a shoulder 35 on the stationary sleeve 23to limit downward movement of the valv 28. 4 A shoulder 36 on the valvehead 3i} engages the shoulder 2'? on the lower end of the sleeve 23 tolimit upward movement of the valve 28.

Spring 86 encircles the stem and acts against a portion of thestationary sleeve 23 to move the valve head 38 toward a seat member 31.

The seat member 3'? is designed to engage with the sealing ring 3! toform a fluid-tight seal.

- This seat 37 is mounted on the lower flexible diaphragm 33 which isannular in form and which is confined on its outer rim between theflange ii on the body and the flange on the lower end cap 18. A retainerring 39 is attached to the seat 3! by means of the bolts 40 and servesto clamp the inner annular portion of the diaphragm 38 between theretainer 39 and the seat 37. From this description, it will beunderstood that a pressure chamber 65 is defined within the lower endcap it and below the diaphragm 38.

The retainer 39 is provided with a central aperture 52 which receivesthe depending stem 43, of a weighted check valve generally designated44. A valve head 45 is threadedly connected to the upper end of the stem43 and is provided with a spherical or conical sealing face 46 which isadapted to engage a corresponding sealing face F i? provided on theunder side of seat member 37.

A relatively weak coil spring it rests on the retainer 39 and engagesthe under side of the valve head The length and strength of spring 48 issuch that check valve e l normally rests between fully closed and fullyopen position.

An upper flexible diaphragm as is confined on its outer diameter betweenthe flange on the upper end cap 2! and the flange 26 on the stationarysleeve 23. This flexible diaphragm :39 is circular and is centrallyattached to the upper end 53 of movable latching sleeve 5 i. A threadedelement 52 cooperates with a retainer ring 53 to clamp the centralportion of the diaphragm 49 to the movable latching sleeve 5!. A coilspring 54 is positioned within the interior of the latching sleeve 53.This spring engages the end 56 of the member 5! at one end and rests onthe stationary sleeve 23 at its other end, and continually urgeslatching sleeve at in an upward direction.

The upper end cap 2| cooperates with the diaphragm 4G to deflne apressure chamber 55. This pressure chamber 55 communicates with thepressure chamber 4| by means of the piping connection 55. From thisdescription it will be understood that when hydraulic pressure ispresent in the service line i8, it is communicated through the nipple idto the pressure chamber and is communicated to the pressure chamber 55by way of the piping connection 5%. Hydraulic pressure in the chamberfill moves the seat 31 and retainer 39 upwardly until the sealingsurface 5] on the seat 3? contacts the sealing ring 3i. Upward movementof the seat 31 is limited by contact of the annular shoulders 21 and 38on the stationary sleeve 23 and valve head 38 respectively. Pressurewithin the chamber 55 moves the latching sleeve 5i downwardly againstthe force of the spring 5 until the shoulder 58 on the stationary sleeve23 engages the shoulder as provided on the underside of the end 50 ofthe latching sleeve 51.

A ported thrust collar 66 encircles the stationary sleeve 23 and isprovided with a central bore 61 which is slidably mounted on the outercylindrical surface 62 of the sleeve 23. A relatively strong coil spring53 encircles the upper portion of the ported thrust collar 60. The lowerend of the spring 53 engages a shoulder 5 on the ported thrust collar i0and the upper end of the spring contacts the annular shoulder on thestationary sleeve 23. The force of the relatively heavy spring 63therefore acts to move the ported thrust collar downwardly, and sincethe lower end 6% of the thrust collar 6% rests on the seat 37, theaction of the spring 63 is to move the seat member 37 downwardly.

Means are provided for normally latching the ported thrust collar 60 inan inoperative position. As shown in the drawings, this means includes aplurality of latching balls 6! each positioned in a slot 68 provided inthe stationary sleeve 23. The diameter of each ball 6! is greater thanthe thickness of the sleeve 23. An annular groove 69 is provided on theinner surface of the ported thrust member 80, and a similar annulargroove '50 is provided on the outer surface of the lower end of thelatching sleeve 5!. From a consideration of Figures 2, 3 and 4, it willbe apparent that the latching balls 6i can assume one of two positions:the balls can extend inwardly into the groove 7! or can extend outwardlyinto the groove 59. In any event, the balls must extend into one of thegrooves because the diameter of each is greater than the thickness ofthe stationary sleeve 23.

When the latching balls 51 extend outwardly into the groove 69, as shownin Figure 1, the ported thrust member 69 is latched in an inoperativeposition and the spring 63 is prevented from moving the thrust member Edin a downward direction. On the other hand, when the latching balls 61extend into the circumferential groove iii, as shown in Figures 3 and 4,the spring 53 moves the ported thrust member 8-3 downwardly to move theseat 3'! away from the sealing ring 3! of the valve 28. When thelatching balls is? extend inwardly into the groove iii, the latchingsleeve 5! is held against axial movement.

The operation of the device will now be de scribed for a complete cycleof operation beginning with the parts in normal operating condition withthe system under pressure. As shown in Figure 2, normal pressurescommunicated to the pressure chamber t! through the nipple it maintainthe seat 31 against the sealing ring 31 on the valve 28 to preventescape of water. The

apse-52s 5 weighted check valve -44rests 'on the relatively weakspring48, and since there is no differential pressure across the valvehead 45 it drops away "from the seat 41 under the action of gravity. *Solong as the pressure in the chamber 4| remains above a predeterminedvalue the parts remain in the position shown in Figure 2. The latchingballs 61 extend radially outwardly into the groove 69.

Should the unit pressure in the chamber "4| fall below suchpredetermined value, for example, ten pounds per square inch, the thrustmember '60 under force of the spring 63 will move down- "wardly'a smallamount until all slack or lost motion'is taken up between the latchingballs "6! and the groove 69. This slight downward -movement of thethrust'member 60 does not result in separation of the sealing ring3l andsealing surface5'l because the clearance under the .nut'34 on valve28permits the valve 28 to move downwardly relative to the fixed sleeve 23for a short distance. The latching balls 6'! effectively latch theported thrust member 68 against further downward movement unless theunit pressure in the chamber 4| continues to fall.

Should the pressure in the chamber 4! fall to a dangerously low value,for example, two pounds per square inch gauge pressure, the unitpressures in chambers 4| and 55 immediately fall to the same low value.The spring 54 then moves the latching sleeve 5| upwardly against the lowunit pressure existing in the chamber'55. When the annular groove H1 inthe latching sleeve 5| reaches a position immediately adjacent to theballs 61, the latter, due to the bevelled edges of the grooves, arethrust radially inwardly so that .they enter the groove 10 and areretracted from the groove 69. This action releases the latching effectof the balls 6'! on the ported thrust member 50. The spring 53 thenmoves the ported thrust member 6|! downward with great force, and thisdrives the seat member 31 downward to the extreme lower position shownin Figure 3. This action separates the sealing ring 3| on the valve 28from the sealing surface 51 on the seat 31.

It will be understood that separation of the valve28 and seat 31 mayoccur before a partial vacuum exists in the chamber 4|, for examplewhenthe unit pressure therein has fallen to the dangerously low value oftwo pounds per square inch. If the unit pressure in the chamber 4|conrtinues to fall so thatactual vacuum conditions exist, atmosphericair is drawn inwardly throughthe ports in the body I5 andports 14:.inthe member. $0, through the annular space vrbetween the sealing ring 3|and sealing surface -51, through the central opening l3 and into thespace 12 which communicates withthe chamber 4|. Atmospheric air is thusdrawn into the nipple l4.

"Should the unit pressure in the chamber ll remain at a dangerously lowvalue,-for example, between zero'and two" pounds persquare' inch gaugepressure, the water in the chamber 5| valve face 46. Excessive loss ofwater under initially to store energy in thespring-FSB. *S' oulddangerously low unit pressuresis'thusefiectively prevented.

If the unit pressure inthe chamber subsequently returns to itsusual-operating range, the

weighted check valve 44 is carried to its extreme upper position asshown in Figure 4,- thereby preventing escape of water except for therelatively small flow through the'groove 1'16. ltwill be observed thatat this time'the' diaphragm 38 and seat 31 are urged downwardlyby theforce of spring 53 acting through ported thrust collar '60. As the unitpressure inchamber 4| increases the seat member is moved upwardly,causing the ported thrust collar fill to rise' and compress thespringfil. This stores'energy in the spring 63 and compresses it to itscocked position shown in Figure i. As the seat member-31 rises thesealingsurface 57 contacts thesealring 3| on the valve 23, therebymaking an eiiective seal and preventing the further-escape of any water.The

seat member-3'5 rises until the shoulder'tt contacts the shoulder 2T,thereby preventing further upward movement of the seat't'i. Asthe seatmember El rises,- compressing the spring '53,

ring 3! the unit pressure above and belovrthe valve head 55 is equalizedthrough the groove '58, and consequently the check valve ttdrops to'anintermediate position asshown inFigure 2.

It will be understood'that thestrength' of the springiit maybe chosento'giveany force desired. I have found that satisfactory performance "isobtained, howevenwhen its strength is such that a uni pressure of aboutten pounds per square inch in the chamber'lii 'issufiicient to "compressthe spring and. move the thrust" member- E9 upwardlyto'latohingposition.

From the above description it wilhbe understood that the pressure of theliquid. is-used the liquid pressure later fall to a clangeron value thevalve is opened to vent the 31113131 to atmosphere'ancl the force actingto ope" valve is derived from'theenergy previously stored in the spring.The-difierential between atmospheric pressure andsuction pressure whichmay exist in the service line is not relied upon to-develop a forcesufficient to open the vacuum breaker valve. The valve is openedpositively by atively" large force of the spring -E3, and the re duceolpressure in the'service line is only for tripping the latching device.Accordingly, the vacuum breaker valve is opened toadmit atmosphericpressure even though the parts the valve may be encrusted--with-mineraldeposits following a long period or inaction.

is of the iullscope of-the appendedclainis.

-I claim: l.v In a vacuum.-breaker assernbly -the.combination of; meansproviding a chamber, a valve for venting the chamber to atmosphere, aspring acting to open the valve, means responsive to fluid pressure insaid chamber adapted to deflect the spring to store energy therein, alatch device acting independently of the valve for normally maintainingthe spring in deflected position, and fluid pressure responsive meansarranged to trip the latch device to enable the energy stored in the sp'ing to open the valve.

2. In a vacuum breaker assembly, the combination of: means providing achamber, a valve for venting the chamber to atmosphere, stored energymeans acting to open the valve, cooperating parts responsive to fluidpressur in said chamber adapted to store energy in said means, a latchdevice acting independently of the valve for normally maintaining saidmeans in storedenergy condition, and fiuid pressure responsive meansarranged to trip the latch device to enable the energy stored in saidmeans to open the valve.

3. In a vacuum breaker assembly, the combination of: a body having achamber therein and a conduit connection communicating with saidchamber, a valve having a pair of relativel movable par'ts adapted inclosed position to confine fluid pressure within the chamber and in openposition to vent the chamber to atmosphere, a spring operativelyconnected to eiiect relative movement of the valve parts toward openposition, a latch device acting independently uf the valve for normallymaintaining the spring inactive, means responsive to fluid pressure insaid chamber for retracting the thrust element to latching position, andfluid pressure responsive means arranged to trip the latch device whenfluid pressure in the chamber falls below a predetermined value.

4. In a vacuum breaker assembly, the combination of a body having achamber therein and a conduit connection communicating with saidchamber, a valve having a pair of relatively movable parts adapted inclosed position to confine iluid pr ssure within the chamber and in openposition to vent the chamber to atmosphere, a spring operativelyconnected through a thrust element to eiiect relative movement of thevalve parts toward open position, the thrust element being mounted formovement relative to the valve, a latch device acting on the thrustelement for normally maintaining the spring inactive, means responsiveto fluid pressure in said chamber for retracting the thrust element tolatching position, and fluid pressure responsive means arranged to tripthe latch device when fluid pressure in the chamber falls below apredetermined value.

5. In a vacuum breaker assembly, the combination of a body having achamber therein and conduit connection communicating with said chamber,a valve assembly within the body including a pair of relatively movableparts, one of the parts having a vent opening communicating with saidchamber and with space exterior to said body, the other part beingarranged to close the opening, means responsive to fluid pressure in thechamber for maintaining the valve parts in closed position, resilientmeans opposing said pressure-responsive means, a releasable latch devicenormally maintaining the resilient means inactive, and fluidpressure-responsive means arranged to trip the latch device whenpressure in said chamber falls below a predetermined value, whereby theresilient means may efiect relative movement between the valve parts tovent the chamber through said vent opening,

6. In a vacuum breaker assembly, the combination of a body having achamber therein and a conduit connection communicating with saidchamber, a valve assembly within the body including a pair of relativelymovable parts, one of the parts having a vent opening communicating withsaid chamber and with space exterior to said body, the other part beingarranged to close the opening, means responsive to fluid pressure in thechamber for maintaining the valve parts in closed position, a coilspring opposing said pressure-responsive means, the pressure-responsivemeans being adapted under high pressure conditions in the chamber todeflect the spring and store energy therein, a releasable latch devicenormally maintaining the spring in deflected position, and additionalfluid pressure-responsive means arranged to trip the latch device whenpressure in said chamber falls below a predetermined value, whereby theenergy stcred in the spring may efiect relative movement between thevalve parts to vent the chamber through said vent openin 7. In a vacuumbreaker assembly, the combination of a body having a chamber therein anda conduit connection communicating with said chamber, a valve assemblyWithin the body including a pair of valve parts mounted for relativeaxial movement, one of the parts having a vent opening communicatingwith said chamber and with space exterior to said body, the other partbeing arranged to close the opening, coaxial means responsive to fluidpressure in the chamber for maintaining the valve parts in closedposition, a coaxial spring opposing said pressureresponsive means, areleasable latch device Within the body normally maintaining the springinactive, and fluid pressure-responsive means arranged to trip the latchdevice when pressure in said chamber falls below a predetermined value,whereby the spring may move one of the valve parts axially away from theother to vent the chamber through said vent openin 8. In a vacuumbreaker assembly, the combination of a body having a chamber therein anda conduit connection communicating with said chamber, a valve assemblywithin the body including a valve head and a movable valve seat, thevalve seat having a vent opening communicating with said chamber andwith space exterior to said body, the valve head being arranged to closethe opening, means responsive to rluid pressure in the chamber f ormaintaining the valve seat and valve head in closed position, resilientmeans opposing said pressure-responsive means, a releasable latch devicenormally maintaining the resilient means inactive, and additional fluidpressure responsive means arranged to trip the latch device whenpressure in said chamber falls below a predetermined value, whereby theresilient means may move the valve seat away from the valve head to ventthe chamber through said vent opening.

9. In a vacuum breaker assembly, the combination of: a body having achamber therein and aconduit connection communicating with said chamber,a valve assembly within the body including a pair of valve parts mountedfor relative axial movement, one of the parts having a vent openingcommunicating with said chamber and with space exterior to said body,the other part being arranged to close the opening, coaxial meansresponsive to fluid pressure in the chamber for maintaining the valveparts in closed position, means opposing said pressure-responmesa-52s..

sive means, said meansincludinga thrustelemerit interposed between aspring and the first of said, valve parts, said pressure-responsivemeansbeing adapted to act. on the thrust element to deflect the springto store energy therein, a releasable latc device acting upon the thrusteiement for normally maintaining the spring in deflected position, andadditional fluid pressure-responsive means arrangedto trip the latchdevice when pressure in said chamber falls below a predetermined value,whereby the spring may act through the thrustelementto move saidfirst-valve part axially away from the other valve part to vent thechamber through said vent opening.

10. In a vacuum breaker assembly, the com bination of: a body having achamber therein and a conduit connection communicating with saidchamber, a valve assembly within the body including a pair of valveparts mounted for rela tive axial movement, one of the parts having avent opening communicating with said chamber and with space exterior tosaid body, the other part being arranged to close the opening, coaxialmeans responsive to fluid pressure in the cham ber for maintaining thevalve parts in closed position, means opposing said pressure-responsivemeans, said means including a thrust element interposed between a springand the first of said valve parts, said pressure-responsive means beingadapted to act on the thrust element to store energy in said spring, areleasable latch device acting upon the thrust element for normallymaintaining the spring in stored energy position, additional fluidpressure responsive means arranged to tri the latch device when pressurein said chamber "falls below a predetermined value, and a check valvecarried on the valve part having the vent opening, thecheck valve havingmeans acting to minimize flow of fluid from the chamber outward throughthe vent opening.

11. In a vacuum breaker assembly, the combination of: a body having achamber therein and a conduit connection communicating with saidchamber, a pair of relatively movable valve parts each mounted for axialmovement on the body, the valve parts being adapted in closed positionto confine fluid pressure within the chamber and in open position tovent the chamber to atmosphere, a spring operatively connected to moveone of the valve parts to effect relative movement of the valve partstoward open position, a latch device normally maintaining the springinactive, abutment means on the body preventing further axial movementof the other valve part after the latch device is fully released, andfluid pressure-responsive means arranged to trip the latch device whenpressure in the chamber falls below a predetermined value, whereby thespring may move the first said valve part away from the other valve partto vent the chamber to atmosphere.

12. In a vacuum breaker assembly, the combination of: a body, a valveassembly including an axially movable valve seat and an axially movablevalve head, a diaphragm connecting the valve seat to the body, thediaphragm cooperating with the valve seat and body to form a chamber,the valve seat having a vent opening communicating with said chamber andwith space exterior to said body, a conduit connection communicatingwith said chamber, the valve head being mounted upon the body andarranged to close the opening, the diaphragm being respon- 1.0; sive-tofluid pressure in the chamber for maintainingthe valve head and seat inclosed position, a spring, a, thrust element interposed between the,spring and the valve seat, a releasable i latch device acting vuponthethrust element for ment and-valve sea-t awayv from the valve head tovent the chamber throughsa-id vent opening.

13. In a vacuumbreaker; assembly, the combination of: abody having achamber therein and aconduit connectioncommunicating with the chamber, avalve having-a pair of relatively movable parts adapted in closedposition to confine pressure within-the chamber and in open position tovent the pressure to atmosphere, means including a-spring operativelyconnected to effect relative movement of the valve parts toward openposition, said means also including a'thrust element adapted to-engageone of the valve parts, a latch device acting on the thrust element formaintaining the spring inactive, the latch device including a centralstationary member adjacent the thrust element and a movable memberslidably' mountedwithrespect to'thestationary member, thestationaryumember having atransverse opening, extending through a Wallthereof, a ball received in said opening, the diameter of the ball beinggreater than the thickness of the wall, the thrustelement andthe movablemember each being providedwith a recess to receive a projecting portionof the ball so that either the movable member orthe thrustelement may besecured with respect to the stationary member, and fluidpressure-responsive means for moving the movable member with respect tothe stationary member when pressure in the chamber falls below apredetermined value.

14. In a vacuum breaker assembly, the combination of: a body having achamber therein and a conduit connection communicating with the chamber,a valve having a pair of relatively movable parts adapted in closedposition to corn fine pressure within the chamber and in open positionto vent the pressure to atmosphere, means including a spring operativelyconnected to effect relative movement of the valve parts toward openposition, said means also including a thrust element adapted to engageone of the valve parts, a latch device acting on the thrust element formaintaining the spring inactive, the latch device including a centralstationary tubular member on which the thrust element is mounted, innermovable sleeve slidably mounted within the stationary tubular member,the stationary tubular member having a plurality of transverse openingsextending through the wall thereof, a ball received in each of saidopenings, the diameter of the balls being greater than the thickness ofthe wall, the thrust element and the movable sleeve each being providedwith recesses to receive a projecting portion of the balls so thateither the inner sleeve or the thrust element may be secured withrespect to the stationary tubular member, and fluid pressure-responsivemeans for moving the sleeve with respect to the station" ary tubularmember when pressure in the chainber falls below a predetermined value,

15. In a vacuum breaker assembly, the combination of a body having achamber therein and a conduit connection communicating with saidchamber, a valve assembly including a pair of relatively movable parts,the first valve part having a vent opening communicating with saidchamber and with space exterior to the body, the second valve part beingarranged to close the opening, said second valve part being capable oflimited axial movement to maintain closure with the first valve partduring partial travel thereof, said first valve part being capable ofgreater axial movement to effect separation of the valve parts and openthe chamber to said space, means including a spring operativelyconnected to effect relative movement between said valve parts towardopen position, said chamber including fluid pressure-responsive meansfor simultaneously moving the first valve part axially toward the secondvalve part to close the opening and to move said spring to retractedposition, means including a releasable latch device for normallymaintaining the spring in retracted position, and a second pressureresponsive means operatively connected with said chamber adapted to tripsaid latch device when the pressure in the chamber falls below apredetermined value, whereby the spring may eifect relative movementbetween the valve parts to vent the chamber through said opening,

16. In a vacuum breaker assembly, the combination of: a body having achamber therein, means including a valve assembly providing a passagefor venting the chamber to atmosphere, the valve assembly havingrelatively movable parts, the valve parts having a fluid pressureresponsive area exposed to atmosphere whereby atmospheric pressure tendsto effect relative movement of the valve parts toward open position, thevalve parts also having a fluid pressure responsive area exposed tofluid pressure in said chamber whereby said fluid pressure tends toeffect relative movement of the valve parts toward closed position,means including a spring operatively connected to effect relativemovement of the valve parts toward open position, a latch deviceoperable to maintain the spring inactive, and fluid pressure responsivemeans arranged to trip the latch device and effect opening movement ofthe valve parts to vent the chamber to atmosphere when fluid pressure inthe chamber falls below a predetermined value.

17. In a vacuum breaker assembly for a water line, the combination of: avalve body having an inlet and an outlet open to atmosphere, cooperatingvalve parts in the body adapted when in open position to connect saidinlet to said outlet, force means including an element acting to efiectrelative movement of the valve parts toward open position, a latchacting independently of the valve parts for holding said force meansinoperative, means responsive to pressure in the inlet for retractingsaid element to latching po sition, and trigger means responsive tofluid pressure within the inlet and operative to release the latch whenthe fluid pressure in the inlet falls to a predetermined value.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,461,010 Amdursky July 3, 1923 2,363,123 Franck Nov. 21, 19442,396,315 Blum Mar. 19, 1946 2,484,940 Franzheim Oct. 18, 1949 FOREIGNPATENTS Number Country Date 831,778 France 1938

